2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Berkeley Software Design Inc's name may not be used to endorse or
13 * promote products derived from this software without specific prior
16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
33 * Machine independent bits of mutex implementation.
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
39 #include "opt_adaptive_mutexes.h"
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_sched.h"
44 #include <sys/param.h>
45 #include <sys/systm.h>
49 #include <sys/kernel.h>
52 #include <sys/malloc.h>
53 #include <sys/mutex.h>
55 #include <sys/resourcevar.h>
56 #include <sys/sched.h>
58 #include <sys/sysctl.h>
59 #include <sys/turnstile.h>
60 #include <sys/vmmeter.h>
61 #include <sys/lock_profile.h>
63 #include <machine/atomic.h>
64 #include <machine/bus.h>
65 #include <machine/cpu.h>
69 #include <fs/devfs/devfs_int.h>
72 #include <vm/vm_extern.h>
74 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
75 #define ADAPTIVE_MUTEXES
79 #include <sys/pmckern.h>
80 PMC_SOFT_DEFINE( , , lock, failed);
84 * Return the mutex address when the lock cookie address is provided.
85 * This functionality assumes that struct mtx* have a member named mtx_lock.
87 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
90 * Internal utility macros.
92 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
94 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
96 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
98 static void assert_mtx(const struct lock_object *lock, int what);
100 static void db_show_mtx(const struct lock_object *lock);
102 static void lock_mtx(struct lock_object *lock, uintptr_t how);
103 static void lock_spin(struct lock_object *lock, uintptr_t how);
105 static int owner_mtx(const struct lock_object *lock,
106 struct thread **owner);
108 static uintptr_t unlock_mtx(struct lock_object *lock);
109 static uintptr_t unlock_spin(struct lock_object *lock);
112 * Lock classes for sleep and spin mutexes.
114 struct lock_class lock_class_mtx_sleep = {
115 .lc_name = "sleep mutex",
116 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
117 .lc_assert = assert_mtx,
119 .lc_ddb_show = db_show_mtx,
122 .lc_unlock = unlock_mtx,
124 .lc_owner = owner_mtx,
127 struct lock_class lock_class_mtx_spin = {
128 .lc_name = "spin mutex",
129 .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
130 .lc_assert = assert_mtx,
132 .lc_ddb_show = db_show_mtx,
134 .lc_lock = lock_spin,
135 .lc_unlock = unlock_spin,
137 .lc_owner = owner_mtx,
142 * System-wide mutexes
144 struct mtx blocked_lock;
148 assert_mtx(const struct lock_object *lock, int what)
151 mtx_assert((const struct mtx *)lock, what);
155 lock_mtx(struct lock_object *lock, uintptr_t how)
158 mtx_lock((struct mtx *)lock);
162 lock_spin(struct lock_object *lock, uintptr_t how)
165 panic("spin locks can only use msleep_spin");
169 unlock_mtx(struct lock_object *lock)
173 m = (struct mtx *)lock;
174 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
180 unlock_spin(struct lock_object *lock)
183 panic("spin locks can only use msleep_spin");
188 owner_mtx(const struct lock_object *lock, struct thread **owner)
190 const struct mtx *m = (const struct mtx *)lock;
192 *owner = mtx_owner(m);
193 return (mtx_unowned(m) == 0);
198 * Function versions of the inlined __mtx_* macros. These are used by
199 * modules and can also be called from assembly language if needed.
202 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
206 if (SCHEDULER_STOPPED())
211 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
212 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
213 curthread, m->lock_object.lo_name, file, line));
214 KASSERT(m->mtx_lock != MTX_DESTROYED,
215 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
216 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
217 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
219 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
220 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
222 __mtx_lock(m, curthread, opts, file, line);
223 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
225 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
227 curthread->td_locks++;
231 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
235 if (SCHEDULER_STOPPED())
240 KASSERT(m->mtx_lock != MTX_DESTROYED,
241 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
242 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
243 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
245 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
246 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
248 mtx_assert(m, MA_OWNED);
250 __mtx_unlock(m, curthread, opts, file, line);
251 curthread->td_locks--;
255 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
260 if (SCHEDULER_STOPPED())
265 KASSERT(m->mtx_lock != MTX_DESTROYED,
266 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
267 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
268 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
269 m->lock_object.lo_name, file, line));
271 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
272 (opts & MTX_RECURSE) != 0,
273 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
274 m->lock_object.lo_name, file, line));
275 opts &= ~MTX_RECURSE;
276 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
278 __mtx_lock_spin(m, curthread, opts, file, line);
279 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
281 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
285 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
290 if (SCHEDULER_STOPPED())
295 KASSERT(m->mtx_lock != MTX_DESTROYED,
296 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
297 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
298 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
299 m->lock_object.lo_name, file, line));
300 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
301 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
303 mtx_assert(m, MA_OWNED);
305 __mtx_unlock_spin(m);
309 * The important part of mtx_trylock{,_flags}()
310 * Tries to acquire lock `m.' If this function is called on a mutex that
311 * is already owned, it will recursively acquire the lock.
314 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
317 #ifdef LOCK_PROFILING
318 uint64_t waittime = 0;
323 if (SCHEDULER_STOPPED())
328 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
329 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
330 curthread, m->lock_object.lo_name, file, line));
331 KASSERT(m->mtx_lock != MTX_DESTROYED,
332 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
333 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
334 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
337 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
338 (opts & MTX_RECURSE) != 0)) {
340 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
343 rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
344 opts &= ~MTX_RECURSE;
346 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
348 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
350 curthread->td_locks++;
351 if (m->mtx_recurse == 0)
352 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE,
353 m, contested, waittime, file, line);
361 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
363 * We call this if the lock is either contested (i.e. we need to go to
364 * sleep waiting for it), or if we need to recurse on it.
367 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts,
368 const char *file, int line)
371 struct turnstile *ts;
373 #ifdef ADAPTIVE_MUTEXES
374 volatile struct thread *owner;
379 #ifdef LOCK_PROFILING
381 uint64_t waittime = 0;
384 uint64_t spin_cnt = 0;
385 uint64_t sleep_cnt = 0;
386 int64_t sleep_time = 0;
387 int64_t all_time = 0;
390 if (SCHEDULER_STOPPED())
396 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
397 (opts & MTX_RECURSE) != 0,
398 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
399 m->lock_object.lo_name, file, line));
400 opts &= ~MTX_RECURSE;
402 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
403 if (LOCK_LOG_TEST(&m->lock_object, opts))
404 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
407 opts &= ~MTX_RECURSE;
410 PMC_SOFT_CALL( , , lock, failed);
412 lock_profile_obtain_lock_failed(&m->lock_object,
413 &contested, &waittime);
414 if (LOCK_LOG_TEST(&m->lock_object, opts))
416 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
417 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
419 all_time -= lockstat_nsecs();
422 while (!_mtx_obtain_lock(m, tid)) {
426 #ifdef ADAPTIVE_MUTEXES
428 * If the owner is running on another CPU, spin until the
429 * owner stops running or the state of the lock changes.
432 if (v != MTX_UNOWNED) {
433 owner = (struct thread *)(v & ~MTX_FLAGMASK);
434 if (TD_IS_RUNNING(owner)) {
435 if (LOCK_LOG_TEST(&m->lock_object, 0))
437 "%s: spinning on %p held by %p",
439 KTR_STATE1(KTR_SCHED, "thread",
440 sched_tdname((struct thread *)tid),
441 "spinning", "lockname:\"%s\"",
442 m->lock_object.lo_name);
443 while (mtx_owner(m) == owner &&
444 TD_IS_RUNNING(owner)) {
450 KTR_STATE0(KTR_SCHED, "thread",
451 sched_tdname((struct thread *)tid),
458 ts = turnstile_trywait(&m->lock_object);
462 * Check if the lock has been released while spinning for
463 * the turnstile chain lock.
465 if (v == MTX_UNOWNED) {
466 turnstile_cancel(ts);
470 #ifdef ADAPTIVE_MUTEXES
472 * The current lock owner might have started executing
473 * on another CPU (or the lock could have changed
474 * owners) while we were waiting on the turnstile
475 * chain lock. If so, drop the turnstile lock and try
478 owner = (struct thread *)(v & ~MTX_FLAGMASK);
479 if (TD_IS_RUNNING(owner)) {
480 turnstile_cancel(ts);
486 * If the mutex isn't already contested and a failure occurs
487 * setting the contested bit, the mutex was either released
488 * or the state of the MTX_RECURSED bit changed.
490 if ((v & MTX_CONTESTED) == 0 &&
491 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
492 turnstile_cancel(ts);
497 * We definitely must sleep for this lock.
499 mtx_assert(m, MA_NOTOWNED);
504 "contention: %p at %s:%d wants %s, taken by %s:%d",
505 (void *)tid, file, line, m->lock_object.lo_name,
506 WITNESS_FILE(&m->lock_object),
507 WITNESS_LINE(&m->lock_object));
513 * Block on the turnstile.
516 sleep_time -= lockstat_nsecs();
518 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
520 sleep_time += lockstat_nsecs();
525 all_time += lockstat_nsecs();
530 "contention end: %s acquired by %p at %s:%d",
531 m->lock_object.lo_name, (void *)tid, file, line);
534 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested,
535 waittime, file, line);
538 LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time);
541 * Only record the loops spinning and not sleeping.
543 if (spin_cnt > sleep_cnt)
544 LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (all_time - sleep_time));
549 _mtx_lock_spin_failed(struct mtx *m)
555 /* If the mutex is unlocked, try again. */
559 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
560 m, m->lock_object.lo_name, td, td->td_tid);
562 witness_display_spinlock(&m->lock_object, td, printf);
564 panic("spin lock held too long");
569 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
571 * This is only called if we need to actually spin for the lock. Recursion
575 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts,
576 const char *file, int line)
580 #ifdef LOCK_PROFILING
582 uint64_t waittime = 0;
585 int64_t spin_time = 0;
588 if (SCHEDULER_STOPPED())
593 if (LOCK_LOG_TEST(&m->lock_object, opts))
594 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
595 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
596 "spinning", "lockname:\"%s\"", m->lock_object.lo_name);
599 PMC_SOFT_CALL( , , lock, failed);
601 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
603 spin_time -= lockstat_nsecs();
605 while (!_mtx_obtain_lock(m, tid)) {
607 /* Give interrupts a chance while we spin. */
609 while (m->mtx_lock != MTX_UNOWNED) {
610 if (i++ < 10000000) {
614 if (i < 60000000 || kdb_active || panicstr != NULL)
617 _mtx_lock_spin_failed(m);
623 spin_time += lockstat_nsecs();
626 if (LOCK_LOG_TEST(&m->lock_object, opts))
627 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
628 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
631 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m,
632 contested, waittime, (file), (line));
633 LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, spin_time);
638 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
643 #ifdef LOCK_PROFILING
645 uint64_t waittime = 0;
648 int64_t spin_time = 0;
652 tid = (uintptr_t)curthread;
654 if (SCHEDULER_STOPPED())
658 spin_time -= lockstat_nsecs();
664 KASSERT(m->mtx_lock != MTX_DESTROYED,
665 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
666 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
667 ("thread_lock() of sleep mutex %s @ %s:%d",
668 m->lock_object.lo_name, file, line));
670 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
671 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
672 m->lock_object.lo_name, file, line));
673 WITNESS_CHECKORDER(&m->lock_object,
674 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
675 while (!_mtx_obtain_lock(m, tid)) {
676 if (m->mtx_lock == tid) {
681 PMC_SOFT_CALL( , , lock, failed);
683 lock_profile_obtain_lock_failed(&m->lock_object,
684 &contested, &waittime);
685 /* Give interrupts a chance while we spin. */
687 while (m->mtx_lock != MTX_UNOWNED) {
690 else if (i < 60000000 ||
691 kdb_active || panicstr != NULL)
694 _mtx_lock_spin_failed(m);
696 if (m != td->td_lock)
701 if (m == td->td_lock)
703 __mtx_unlock_spin(m); /* does spinlock_exit() */
706 spin_time += lockstat_nsecs();
708 if (m->mtx_recurse == 0)
709 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE,
710 m, contested, waittime, (file), (line));
711 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
713 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
714 LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_time);
718 thread_lock_block(struct thread *td)
722 THREAD_LOCK_ASSERT(td, MA_OWNED);
724 td->td_lock = &blocked_lock;
725 mtx_unlock_spin(lock);
731 thread_lock_unblock(struct thread *td, struct mtx *new)
733 mtx_assert(new, MA_OWNED);
734 MPASS(td->td_lock == &blocked_lock);
735 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
739 thread_lock_set(struct thread *td, struct mtx *new)
743 mtx_assert(new, MA_OWNED);
744 THREAD_LOCK_ASSERT(td, MA_OWNED);
747 mtx_unlock_spin(lock);
751 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
753 * We are only called here if the lock is recursed or contested (i.e. we
754 * need to wake up a blocked thread).
757 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
760 struct turnstile *ts;
762 if (SCHEDULER_STOPPED())
767 if (mtx_recursed(m)) {
768 if (--(m->mtx_recurse) == 0)
769 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
770 if (LOCK_LOG_TEST(&m->lock_object, opts))
771 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
776 * We have to lock the chain before the turnstile so this turnstile
777 * can be removed from the hash list if it is empty.
779 turnstile_chain_lock(&m->lock_object);
780 ts = turnstile_lookup(&m->lock_object);
781 if (LOCK_LOG_TEST(&m->lock_object, opts))
782 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
784 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
785 _mtx_release_lock_quick(m);
788 * This turnstile is now no longer associated with the mutex. We can
789 * unlock the chain lock so a new turnstile may take it's place.
791 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
792 turnstile_chain_unlock(&m->lock_object);
796 * All the unlocking of MTX_SPIN locks is done inline.
797 * See the __mtx_unlock_spin() macro for the details.
801 * The backing function for the INVARIANTS-enabled mtx_assert()
803 #ifdef INVARIANT_SUPPORT
805 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
809 if (panicstr != NULL || dumping)
816 case MA_OWNED | MA_RECURSED:
817 case MA_OWNED | MA_NOTRECURSED:
819 panic("mutex %s not owned at %s:%d",
820 m->lock_object.lo_name, file, line);
821 if (mtx_recursed(m)) {
822 if ((what & MA_NOTRECURSED) != 0)
823 panic("mutex %s recursed at %s:%d",
824 m->lock_object.lo_name, file, line);
825 } else if ((what & MA_RECURSED) != 0) {
826 panic("mutex %s unrecursed at %s:%d",
827 m->lock_object.lo_name, file, line);
832 panic("mutex %s owned at %s:%d",
833 m->lock_object.lo_name, file, line);
836 panic("unknown mtx_assert at %s:%d", file, line);
842 * The MUTEX_DEBUG-enabled mtx_validate()
844 * Most of these checks have been moved off into the LO_INITIALIZED flag
845 * maintained by the witness code.
849 void mtx_validate(struct mtx *);
852 mtx_validate(struct mtx *m)
856 * XXX: When kernacc() does not require Giant we can reenable this check
860 * Can't call kernacc() from early init386(), especially when
861 * initializing Giant mutex, because some stuff in kernacc()
862 * requires Giant itself.
865 if (!kernacc((caddr_t)m, sizeof(m),
866 VM_PROT_READ | VM_PROT_WRITE))
867 panic("Can't read and write to mutex %p", m);
873 * General init routine used by the MTX_SYSINIT() macro.
876 mtx_sysinit(void *arg)
878 struct mtx_args *margs = arg;
880 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
885 * Mutex initialization routine; initialize lock `m' of type contained in
886 * `opts' with options contained in `opts' and name `name.' The optional
887 * lock type `type' is used as a general lock category name for use with
891 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
894 struct lock_class *class;
899 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
900 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
901 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
902 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
906 /* Diagnostic and error correction */
910 /* Determine lock class and lock flags. */
912 class = &lock_class_mtx_spin;
914 class = &lock_class_mtx_sleep;
916 if (opts & MTX_QUIET)
918 if (opts & MTX_RECURSE)
919 flags |= LO_RECURSABLE;
920 if ((opts & MTX_NOWITNESS) == 0)
922 if (opts & MTX_DUPOK)
924 if (opts & MTX_NOPROFILE)
925 flags |= LO_NOPROFILE;
929 /* Initialize mutex. */
930 lock_init(&m->lock_object, class, name, type, flags);
932 m->mtx_lock = MTX_UNOWNED;
937 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
938 * passed in as a flag here because if the corresponding mtx_init() was
939 * called with MTX_QUIET set, then it will already be set in the mutex's
943 _mtx_destroy(volatile uintptr_t *c)
950 MPASS(mtx_unowned(m));
952 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
954 /* Perform the non-mtx related part of mtx_unlock_spin(). */
955 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
958 curthread->td_locks--;
960 lock_profile_release_lock(&m->lock_object);
961 /* Tell witness this isn't locked to make it happy. */
962 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
966 m->mtx_lock = MTX_DESTROYED;
967 lock_destroy(&m->lock_object);
971 * Intialize the mutex code and system mutexes. This is called from the MD
972 * startup code prior to mi_startup(). The per-CPU data space needs to be
973 * setup before this is called.
979 /* Setup turnstiles so that sleep mutexes work. */
983 * Initialize mutexes.
985 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
986 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
987 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
988 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
989 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
990 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
991 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
992 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
993 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
999 db_show_mtx(const struct lock_object *lock)
1002 const struct mtx *m;
1004 m = (const struct mtx *)lock;
1006 db_printf(" flags: {");
1007 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
1011 if (m->lock_object.lo_flags & LO_RECURSABLE)
1012 db_printf(", RECURSE");
1013 if (m->lock_object.lo_flags & LO_DUPOK)
1014 db_printf(", DUPOK");
1016 db_printf(" state: {");
1018 db_printf("UNOWNED");
1019 else if (mtx_destroyed(m))
1020 db_printf("DESTROYED");
1023 if (m->mtx_lock & MTX_CONTESTED)
1024 db_printf(", CONTESTED");
1025 if (m->mtx_lock & MTX_RECURSED)
1026 db_printf(", RECURSED");
1029 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1031 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1032 td->td_tid, td->td_proc->p_pid, td->td_name);
1033 if (mtx_recursed(m))
1034 db_printf(" recursed: %d\n", m->mtx_recurse);